We used to have this problem in Clone Wars when we would try to put Yoda in a story and it would be like, “Yeah, if Yoda’s there, this isn’t really a problem is it?” That’s because Yoda’s going to go in there and kick everyone’s butt. We all felt that Ahsoka, the only person that could really match her in this time period, blow for blow, would be Vader or the Emperor.

"The Grand Master of the Jedi Council was the wisest and most powerful of them all..... After Palpatine fought him to a standstill, Yoda retreated into exile, where he eventually trained Luke Skywalker."

Originally posted by Darth Thor Only Canon quote so far for Yoda stalemating Sidious, plus confirmation that Yoda is more powerful than Mace:

Under Yoda's description:

"The Grand Master of the Jedi Council was the wisest and most powerful of them all..... After Palpatine fought him to a standstill, Yoda retreated into exile, where he eventually trained Luke Skywalker."